Research On Crosswind Stability And Control Strategy Of FSAE Racing Car

With the rapid development of FSAE,the speed of vehicle has increased year by year,and the aerodynamic characteristics of racing car have been greatly developed.The effects of crosswind on handing stability of FSAE racing car have been attracted widespread attention.Currently,adjusting the steering wheel by driver is the main way to correct the body attitude and vehicular path when crosswind acting on vehicle,which will increase driver's burden and have bad effect on the match results and driving safety.In this study,based on the active safety control technology,active front steering is utilized to improve the crosswind stability of FSAE racing car,which has great significance to improve the driving safety and match results.In the study,HRT-16 C racing car is selected as research object,which is from Harbin Institute of Technology Combustion Racing Team.Vehicle dynamic model of HRT-16 C is established,which is the model platform for control strategy's research on crosswind stability of FSAE racing car.Firstly,the magic formula model of Hoosier R25 B tire is established to study the tire longitudinal and lateral mechanical characteristics.According to the tire's nonlinear characteristics,a 4-DOF vehicle dynamic model considering the crosswind's influence is established,which includes the lateral motion,pitch motion,roll motion and yaw motion.In addition,a 2-DOF vehicle dynamic model including the lateral motion and yaw motion is also established as an ideal model for control strategy's research.Three different typical crosswind conditions are researched in this paper: one is the racing car runs in a straight path through the steady crosswind,which is designed according to the ESV standard;the other two are vehicle runs in a curve that is designed based on the track size through the steady vertical reverse crosswind and steady parallel reverse crosswind.In order to improve the reliability of the input model,crosswind model need to be established based on real vehicle parameters and vehicle running condition.Considering the drift of pressure center in straight running condition,the variation law of pressure center is obtained by fitting the data from the real vehicle model.For two different curved running conditions,the aerodynamic force and moment at selected moments are calculated by CFD.Then the variation laws of aerodynamic parameters are gotten by fitting the CFD data.The control strategy for crosswind stability is designed according to the operational principle of AFS.The optimal feedback matrix is obtained of control system by using linear quadratic optimal control theory.In control system,yaw rate and sideslip angle,are selected as control system's state parameters;accessional steering angle is selected as system' control parameter;yaw rate's and sideslip angle's deviations from the ideal values are selected as control system's output parameters.Simulation platform is built by Simulink,which is used to validate the control strategy.According to the simulation results,the yaw rate and lateral displacement could follow the ideal value accurately in three different crosswind conditions;the deviation between the sideslip angle and ideal value is decreased.The results mean that the vehicle handing stability and driving stability are improved under the control,which shows that the control strategy is reasonable and effective.